Her debut novel, The Madams, was published in 2006 and has been called "a racy and hilarious take on the black economic empowerment crowd in Johannesburg".[4] It was shortlisted for the K Sello Duiker Award of the South African Literary Awards (SALA) in 2007.[5] She went on to write three other novels: Behind Every Successful Man (2008), Men of the South (2010), which was shortlisted for the 2011 Commonwealth Writers' Prize (Africa region),[6] as well as the Herman Charles Bosman Award,[7][8] and 2014's London Cape Town Joburg, which won the K Sello Duiker Memorial Literary Award in 2015.[1]

In 2010 she co-authored two works of non-fiction: with South African photographer Alf KumaloA Prisoner’s Home, a biography on the first Mandela house 8115 Vilakazi Street, and L'Esprit du Sport with French photographer Amelie Debray. Wanner is co-editor of the African-Asian short-story anthology Behind the Shadows (2012) with Rohini Chowdhury.[8] In addition Wanner has written two children's books, Jama Loves Bananas and Refilwe — an African retelling of the fairy tale "Rapunzel". In 2018, her third nonfiction work Hardly Working a travel memoir was published by Black Letter Media.

In April 2014, Wanner was named on the Hay Festival's Africa39 list of 39 Sub-Saharan African writers aged under 40 with potential and talent to define trends in African literature.[2]

She is a founding member of the ReadSA initiative, a campaign encouraging South Africans to read South African works.[3][5] She also sat on the pan-African literary initiative, Writivism's Board of Trustees until September 2016. She is a regular participant at international literary events and has conducted workshops for young writers in Zimbabwe, South Africa, Denmark, Germany and Western Kenya.[8][10]

Wanner was also one of three judges of the sole Pan-African literary prize for book-length fiction, the Etisalat Prize for Literature in 2015 and the African juror for the Commonwealth Short Story Prize 2017.She has also been the founder and curator of Artistic Encounters in Nairobi, Kenya.

In 2018, she set up her publishing company, Paivapo, in partnership with her friend and fellow writer Angela Makholwa with a focus on marketing African literature in the Anglophone, Francophone and Lusophone African regions.[11][12]